Quality assessment of the optical thin films using line field spectral domain optical coherence tomography

Shirazi, Muhammad Faizan,Wijesinghe, Ruchire Eranga,Ravichandran, Naresh Kumar,Kim, Pilun,Jeon, Mansik,Kim, Jeehyun Elsevier 2018 Optics and lasers in engineering Vol.110 No.-

<P>In this study, the industrial inspection of optical thin film on touch screen panels was demonstrated using line field spectral domain optical coherence tomography. The conventional Fourier domain optical coherence tomography system requires a single scanner for two-dimensional cross-sectional images and two scanners for volumetric images. Our developed line field spectral domain optical coherence tomography has the advantage of needing only a single scanner for volumetric images, while two-dimensional cross-sectional images are obtained by the parallel acquisition of an illuminated line on a sample using an area camera. Further, the image acquisition speed was enhanced by implementing a high speed camera (340 frames per seconds) with improved quantum efficiency at near infrared region enabling two-fold frame rate. Cross-sectional and volumetric images were acquired to detect the internal sublayer defects in the optical thin films, which are difficult to observe using visual or machine vision-based inspection methods. The developed pseudo code for defect identification in optical thin films was well-utilized here for the defect inspection. The system characterization is demonstrated using United State Air Force (USAF) resolution target. The results indicate the possible application of the proposed system in touch screen panel inspection for the quality assurance of products at the consumer end.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Quality assessment of the optical thin films used for touch screen panel. </LI> <LI> Line illumination is utilized to get the cross-sectional information without scanner. </LI> <LI> The sublayer defects are detected using line field optical coherence tomography. </LI> <LI> A defect detection algorithm is developed for the quality assurance of optical thin films. </LI> <LI> Cross-sectional and three-dimensional images show the effectiveness of the system. </LI> </UL> </P>

결절성경화증에서 망막 성상세포과오종의 안저자가형광, 형광안저혈관조영 및 스펙트럼영역 빛간섭단층촬영 소견

권영기(Young Ki Kwon),강동진(Dong Jin Kang),임종찬(Jong Chan Lim),김종호(Jong Ho Kim),박동호(Dong Ho Park),신재필(Jae Pil Shin) 대한안과학회 2016 대한안과학회지 Vol.57 No.1

Purpose: To analyze the structural and morphological characteristics of retinal astrocytic hamartomas in tuberous sclerosis patients using fundus autofluorescence, fluorescein angiography and spectral-domain optical coherence tomography. Case summary: Fundus examination, fundus autofluorescence, fluorescein angiography and spectral-domain optical coherence tomography were performed in three patients with tuberous sclerosis and the morphological and structural characteristics of retinal astrocytic hamartomas were analyzed. In the fundus autofluorescence, type 1 retinal astrocytic hamartoma showed hypofluorescence and type 3 showed central hyperfluorescence and surrounding hypofluorescence. Spectral domain optical coherence tomography showed dome-shaped hyper-reflectivity within the nerve fiber layer and focal adhesion of the vitreous cortex in the type 1 retinal astrocytic hamartoma. No abnormalities were observed in the outer retinal layer and retinal pigment epithelium. In the type 3 retinal astrocytic hamartoma, optical coherence tomography showed disorganization of retinal tissue and posterior shadowing. Intratumoral cavitation and moth-eaten appearance caused by intratumoral calcification were observed and the vitreous cortex adhered to the top of the tumor and showed traction. Retinal arterial sheathing was observed in all cases and hyper-reflectivity of the arterial wall was noted on optical coherence tomography. Conclusions: Fundus autofluorescence, fluorescein angiography and spectral-domain optical coherence tomography are helpful for the classification and diagnosis of retinal astrocytic hamartomas found in tuberous sclerosis patients as well as for differentiation from other lesions.

Optical Conherence Tomography를 위한 광 헤테로다인 간섭계의 원리 및 구성

정태호,박양하,오상기,김용평 慶熙大學校 레이저 工學硏究所 2002 레이저공학 Vol.13 No.-

Optical Coherence Tomography is a new medical dianostic imaging technology which can perform micron resolution cross-sectional or tomograpic imaging in biological tissue. Basically, Optical Coherence Tomography used the interference effect of Michelson interferometer. In this paper, we analyze the Optical Coherence Tomography system.

Optical Coherence Tomography Based on a Continuous-wave Supercontinuum Seeded by Erbium-doped Fiber’s Amplified Spontaneous Emission

이주한,김창석,Eun Joo Jung 한국광학회 2010 Current Optics and Photonics Vol.14 No.1

In this study, the use of a continuous-wave (CW) supercontinuum (SC) seeded by an erbium-doped fiber’s amplified spontaneous emission (ASE) for optical-coherence tomography imaging is experimentally demonstrated. It was shown, by taking an in-depth image of a human tooth sample, that due to the smooth,flat spectrum and long-term stability of the proposed CW SC, it can be readily applied to the spectral-domain optical-coherence tomography system. The relative-intensity noise level and spectral bandwidth of the CW SC are also experimentally analyzed as a function of the ASE beam power.

시간영역 광 간섭 단층촬영 시스템의 소형 엔도스코프 제작 및 영상구현

김영관,이성헌,김용평,Kim, Young-Kwan,Lee, Sung-Hun,Kim, Yong-Pyung 한국광학회 2010 한국광학회지 Vol.21 No.5

We fabricated and characterized a compact endoscopic catheter for optical coherence tomography. The optical delay line (ODL), composed of a cylindrical piezoelectric transducer (PZT) and an optical fiber, was operated with a 1 kHz sinusoidal driving wave in the time-domain. When the ODL was driven with a sinusoidal wave function, the axial scanning speed was 6 m/s and the axial acquisition rate was 2000 line/s at a depth of about 3 mm. Endoscopic OCT images of a human finger and earhole were successfully obtained with an image rate of ten frames per second. 광 간섭 단층촬영 시스템(OCT)을 위한 소형의 광섬유 도관형 주사장치인 엔도스코프(endoscope catheter)를 제작하였다. 깊이방향 주사장치인 원통형 압전소자(PZT)를 이용한 광경로 지연기는 정현파 1 kHz로 구동하여 시간영역에서 엔도스코프 OCT 영상을 구현하였다. 정현파로 구동한 광경로 지연기의 속도는 6 m/s 이고, 깊이방향 스캐닝의 데이터 획득은 3 mm 기준에서 초당 2000 라인이다. 제작한 엔도스코프로 사람의 손가락 및 귀에 대한 초당 10프레임의 OCT 영상을 성공적으로 획득하였다.

스펙트럼영역 빛간섭단층촬영으로 측정한 당뇨망막병증 환자의 주변부 맥락막두께 측정

이성우(Seong Woo Lee),김재석(Jae Suk Kim) 대한안과학회 2015 대한안과학회지 Vol.56 No.12

Purpose: To evaluate choroidal thickness at the outside of the fovea in patients with diabetic retinopathy using spectral-domain optical coherence tomography. Methods: We examined 87 eyes of 87 patients with diabetic retinopathy and 40 eyes of 40 normal patients. Patients with diabetic retinopathy were divided into 3 groups according to the grade of diabetic retinopathy and macular edema. The choroidal thickness was obtained at the fovea and outside of the fovea using enhanced depth imaging of Spectralis optical coherence tomography. One foveal and 8 peripheral images were selected and choroidal thickness was measured from the outer border of the retinal pigment epithelium to the inner scleral border. Results: Subfoveal choroidal thickness was thinner with increasing severity of diabetic retinopathy. However, there was no significant difference between groups without the nasal side of the fovea. A statistically significant difference was observed over the fovea at the superotemporal area. Conclusions: The choroidal thickness outside of the fovea was thinner with the severity of diabetic retinopathy and was more pronounced in the superotemporal area 목적: 스펙트럼영역 빛간섭단층촬영을 이용하여 당뇨망막병증 환자에서 중심와 및 혈관궁 근처의 주변부 맥락막두께를 측정하여 당뇨망막병증의 중증도에 따른 차이를 알아보고자 하였다. 대상과 방법: 정상 40안, 당뇨망막병증 87안을 대상으로 Heidelberg Spectralis EDI mode를 이용하여 맥락막두께를 측정하였다. 당뇨망막병증 87안은 당뇨망막병증의 중증도와 황반부종의 유무에 따라 3개의 군으로 분류하였다. 맥락막두께는 중심와 주위뿐만 아니라 혈관궁 근처의 주변부를 측정하였으며, 1개의 중심와 주위와 8개의 주변부 이미지를 선택하여 맥락막두께를 비교하였다. 결과: 중심와 아래의 맥락막두께는 당뇨망막병증의 중증도가 심해질수록 얇아지는 경향을 보였으나 통계학적으로 유의한 차이를 보이지는 않았다. 혈관궁 근처의 주변부 맥락막두께 중 상이측의 맥락막두께가 의미 있는 차이를 보였다. 결론: 중심와 및 혈관궁 근처의 주변부 맥락막두께는 당뇨망막병증의 중중도가 심해질수록 얇아지는 경향을 보였으며, 상이측의 주변부에서 두드러진 것을 알 수 있었다.

Optical Coherence Tomography를 이용한 원발성 맥락망막염 이환견의 진단 및 치료

지동범,정만복,유석종,서강문 한국임상수의학회 2013 한국임상수의학회지 Vol.30 No.4

A 5-year-old intact male Yorkshire terrier dog was referred with a 1-week history of blindness. In both eyes, menace responses and pupillary light reflexes were absent. The indirect ophthalmoloscopy revealed multiple small gray-white and discoloration lesion in mid-nontapetum area in both eyes. Electroretinograms showed diminished amplitude of a- and b-waves. Multifocal serous retinal detachments were detected with optical coherence tomography (OCT) over the small gray-white and discoloration lesion in the fundus. After one week of treatments, the indirect ophthalmoloscopy showed that irregular patches and hyperpigmentation in the center of hyperreflectivity area. Reattachment and retinal thinning were observed by the OCT. The results indicate that OCT scanning is considered to be a useful method for retinal evaluation in dogs with chorioretinitis.

혈관빛간섭단층촬영을 이용한 정상인과 당뇨망막병증 환자에서의 망막중심오목 무혈관부위 분석

김인근,이주은 대한안과학회 2017 대한안과학회지 Vol.58 No.8

Purpose: To evaluate the effectiveness of optical coherence tomography angiography (OCTA) in investigating changes in the area of the foveal avascular zone (FAZ) in patients with diabetic retinopathy (DR) and normal subjects. Methods: Eighty-five eyes of 50 DR patients and 50 eyes of 25 normal subjects were included. OCTA images of the FAZ were acquired using the split-spectrum amplitude decorrelation angiography algorithm of Optovue Avanti RTVue XR OCT. Patients were divided into three groups according to DR severity: mild-to-moderate non-proliferative diabetic retinopathy (NPDR) group, severe NPDR group, and proliferative DR group. The area of the FAZ was measured using built-in software and was compared between the patients and normal subjects and among the three groups. Results: The area of the FAZ in patients with diabetic retinopathy (0.46 mm2) was significantly larger than that in normal subjects (0.30 mm2, p = 0.001). A significant difference was observed depending on DR severity: 0.40 mm2 in the mild-to-moderate NPDR group, 0.45 mm² in the severe NPDR group, and 0.53 mm2 in the PDR group (p = 0.03). Correlation between area of the foveal avascular zone and visual acuity showed a tendency toward reduction in visual acuity (p = 0.002). Conclusions: OCTA effectively detected changes in the FAZ area in DR patients. OCTA has the potential to be used for noninvasive quantification and monitoring of the FAZ. 목적: 당뇨망막병증 환자를 대상으로 혈관빛간섭단층촬영을 이용하여 망막중심오목 무혈관부위를 측정하고 정상 대조군과 비교하여 혈관빛간섭단층촬영의 임상적 유용성에 대해 알아보고자 하였다. 대상과 방법: 당뇨망막병증 50명 85안과 정상 대조군 25명 50안을 비교 대상으로 하였다. Optovue Avanti RTVue XR optical coherence tomography를 이용하여 망막중심오목 무혈관부위의 혈관 영상을 얻은 후 면적측정 기능을 이용하여 망막중심오목 무혈관부위의 면적을 측정하고, 정상인과 당뇨망막병증 환자에서의 차이, 당뇨망막병증의 진행정도에 따른 차이를 비교하였다. 당뇨망막병증 환자는 진행 정도에 따라 경도-중등도 비증식당뇨망막병증, 심한 비증식당뇨망막병증, 그리고 증식성당뇨망막병증으로 나누어 비교하였다. 결과: 당뇨망막병증 환자의 망막중심오목 무혈관부위(0.46 mm2)는 정상 대조군(0.30 mm2)에 비해 의미 있게 넓게 측정되었다(p=0.001). 망막중심오목 무혈관부위를 당뇨망막병증의 정도에 따라 비교했을 때 세 군 간의 의미 있는 차이를 보였다(경도-중등도비증식당뇨망막병증; 0.40 mm2, 심한 비증식당뇨망막병증; 0.45 mm2, 증식성당뇨망막병증; 0.53 mm2, p=0.03). FAZ의 면적과 최대교정시력과의 연관성을 조사하였을 때 FAZ가 넓어질수록 시력이 떨어지는 음의 상관관계를 보였다(p=0.002). 결론: 혈관빛간섭단층촬영은 당뇨망막병증 환자에서 망막중심오목 무혈관부위를 비침습적으로 측정하고 이를 정량화할 수 있어, 당뇨망막병증의 경과 관찰에 유용하게 활용할 수 있을 것으로 사료된다.

Overnight Orthokeratology 콘택트렌즈의 착용에 의한 각막두께의 변화

최정훈,남상훈,오현진,마기중 대한시과학회 2002 대한시과학회지 Vol.4 No.1

Ov앉night Orthokeratology 콘핵트렌즈 착용자 28명 (56안}을 대상으로 각막두께의 변화률 분삭하가 위하여 Optical Coherence Tomography와 Orbscan Pachymetry System올 이용하여 렌즈 착용 전과 렌즈 착용 1 개월 후의 각막중심부 두께를 측정하였다. Ortho-K 콘택트렌즈률 착용하기 전 Optical Coherence Tomography와 Orbscan Pachymetrγ System으로 측정한 각막중심부 두째는 517.7 :t 33.4 /ßII와 530.4 :t 42.1 /ßII로 Orbscan Pachymetrγ Sys따n으로 측정 한 값야 12.7 μm 정 도 더 두꺼 웠고(t = 7.01, p = O.αxx>>, 푸 측정값 사이에 높은 상관판계가 있었다(OCT 측정값= 112.8 + 0.71없4 x OPS 측정값; r == 0.96, p < O.α)()1). Ortho-K 콘태트렌죠훌 1 개월 홍안 확용하였옳 때 각막 중성 부 두께의 벌향는 〔빼cal Coh없nce Tomogra야lY 측정 값α114.9 土9.3 /ßI1(514.3 土38.9 짜에 서 499.4 土40.7 따1), Orbscan Pachyme따T System 측정 값이 8.5 ::t 15.6 때1(526.0 土49.1 때1에 서 517.5 ::t 42.6 짜} 각각 감소하였으나(OCT : t = 5.81, p =: O.αX>; 0똥 : t := 2.72, p == 0.016), 두 기기로 측정한 작막두께의 평균 변화도는 유의한 차이가 없었으며 (t = -0.84, p == 0‘ 416), Orbscan Pachymetry System으로 촉정 한 각막 풍간주변부 두쩨논 14 따l 정 도 증가하였다. To evaluate the change of comeal thickness after wearing OI당lokeratology contact lenses, the central comeal thickness was measured at baseline and 1 rnonth 따ter W많ring contact lens using Opti떠1 Coherence Tomograhy and Orbscan Pachymetry System. πle 않ntral comeal thickness measured by ()Ptical Coherence Tornography and Orbscan Pachymetry System at baseline were 517.3 :t 33.4 f.lIll 때d 530.4:t 42.1 f.lIll resκ~tively, and the mean of two diff,앉‘ent measurements showed statistically significant difference(p = O.αXX)()). The central comeal thickness measured by Optic머 Coh얹"ence Tomograhy and Orbscan Pachymetry System were highly correlated(OCT measurem얹Jts = 112.8 + 0.7'κ34 x OPS measurements). The central comeal thickness at 1 month after wearing Orthokeratology contact lens measured by Optical Coherence Topography and Orbscan Pachymetry System were reduced by 14.9 :t 9.3 μm 없d 8.5 :t 15.6 f.lIIl res야:x::tively. There were no significant ch없1ge of cenσal comeal thickness measured by two different systems. After wearing the orthokeratology contact lenses for one month, the mid-p퍼pheraI com얹1 thickness measured by Orbscan Pachymetry Syst없1 showed significantly thicker of 14 때 than those of baseline.

Classification of human gingival sulcus using swept-source optical coherence tomography: <i>In vivo</i> imaging

Lee, Jaeyul,Park, Jaeseok,Faizan Shirazi, Muhammad,Jo, Hosung,Kim, Pilun,Wijesinghe, Ruchire Eranga,Jeon, Mansik,Kim, Jeehyun Elsevier 2019 Infrared physics & technology Vol.98 No.-

<P><B>Abstract</B></P> <P>We demonstrated a preliminary research to investigate the feasible <I>in vivo</I> utilization of swept-source optical coherence tomography (SS-OCT) system with 1310 nm wavelength band to obtain morphological visualizations and human gingival sulcus depth measurements. Apart from the cross-sectional analysis, pixel intensity based OCT image classification algorithm is developed to identify the depth of gingival sulcus quantitatively. A total of 43 sites from the periodontal tissues of five healthy individuals were imaged <I>in vivo</I> by using the OCT system. Two periodontal tissues were right and left maxillary central incisors, while the other four periodontal tissues were left and right mandibular central incisors and later incisors. The developed classification algorithm could measure the gingival sulcus depths, which are 1.15 ± 0.21 mm of the maxilla and 1.06 ± 0.27 mm of the mandible. The averaged total depths obtained by the system was 1.10 ± 0.26 mm. Hence, the gingival sulcus depth could be quantitatively measured by using the swept-source OCT system with the developed image classification algorithm as well as revealing a structural visualization, which ultimately confirmed the potential applicability for gingival sulcus depth real-time assessment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SS-OCT was utilized to visualize human gingival sulcus <I>in vivo</I> for the depth identification. </LI> <LI> The quantitative measurement was enhanced by applying the developed OCT image classification algorithm. </LI> <LI> Total of 43 sites from the periodontal tissues of five healthy individuals was imaged. </LI> <LI> The classification of gingival sulcus was helpful to confirm the depth of maxilla and mandible regions. </LI> <LI> The proposed method can be anticipated that provides a powerful tool to the periodontal-OCT applications. </LI> </UL> </P>